Growth rate, doping, and compositional uniformity in an atmospheric-pressure multiwafer OMVPE reactor

Abstract

The cost effective production of many III–V epitaxial semiconductor devices, particularly large area devices such as solar cells, depends in part on the development of multiwafer organometallic vapor phase epitaxy (OMVPE) reactors that produce wafers with sufficient uniformity in thickness, doping and composition. For the atmospheric-pressure reactor discussed in this work, the material nonuniformities are dominated by deviations from uniform geometry in the reactor tube and susceptor stand, as shown by improvements following the redesign of the susceptor to be more tolerant of reactor geometry. The results are comparable to uniformities seen in multiwafer reactors operated at reduced pressures and enable batch growth of GaAs solar cells whose energy conversion efficiencies vary by less than ±0.5%. The reactor also exhibits a moderately high compositional variation in AlxGa1 − x over a single wafer and a strong compositional variation with growth temperature. The variations in growth rate, dopant incorporation and composition can be described in terms of reactor growth dynamics in the presence of stable thermally driven convection cells.